CHAPTER XXII 

 ORGANIC ADAPTATION 



Every creature is a bundle of adaptations. Indeed, when we take 

 away the adaptations, what have we left? — Thomson and Geddes. 



Since organisms are dependent for their life processes upon 

 energy liberated by physico-chemical processes in protoplasm, any 

 and all influences which induce changes in the structure or func- 

 tions of an organism must initially modify the underlying meta- 

 bolic phenomena. In other words, organic response is a problem 

 of metabolism. Although it is highly important that this cardi- 

 nal fact be clearly grasped, the science of biology to-day is not 

 in a position to interpret the responses of organisms in these 

 fundamental terms. Accordingly we can merely present some 

 representative instances to illustrate the fact that the response 

 of organisms, as exhibited in active adjustment — adaptation — 

 of internal and external relations, overshadows in uniqueness all 

 other characteristics of life and at one stroke differentiates even 

 the simplest organism from the inorganic. 



Overwhelmingly striking as is the fitness of organisms to their 

 physical surroundings, we must not lose sight of the fact that the 

 environment itself presents a reciprocal fitness. This results from 

 the 'unique or nearly unique properties of water, carbonic 

 acid, the compounds of carbon, hydrogen, and oxygen. . . . No 

 other environment consisting of primary constituents made up of 

 other known elements, or lacking water and carbonic acid, 

 could possess a like number of fit characteristics, or in any 

 manner such great fitness to promote complexity, durability, 

 and active metabolism in the organic mechanism which we call 

 life." (Henderson.) 



A. Adaptations to the Physical Environment 



In any consideration of the reciprocal relations which must 

 exist between organisms and their surroundings, of first importance 

 is the inconstancy of the latter. Uncertainty is the one certainty 

 in nature and accordingly the response of living things — their 



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